I graduated in Philosophy last year (June 2014) and am now on a grad scheme for a commercial insurance and risk firm. Whilst I was in uni I worked in a call centre selling home insurance and this was what really pushed me up the employability ladder. Philosophy is not vocational so won't necessarily lead you to a job, but if you can combine it with practical work experience in a specific industry then you should be fine.
As you are in year 12, really make sure you nail your A-Levels as these will be surprisingly useful when applying for graduate roles, with some of the big schemes and opportunities requiring minimum UCAS points or at least a certain level of grades in top three a-levels.
Might be worth looking in to accountancy (PWC, EY, KPMG, Deloitte, Saffery Champness - Go to accounts age for a big list), as they often don't ask for specific degrees so Philosophy is as useful as anything else.
Keep studying and good luck in whatever subject you decide to do!